The participants who participated in this study were 426 5th and 6th grade students from three elementary schools located in P metropolitan city. An independent samples t-test was conducted to determine differences in individual interest in science, interest-type curiosity, deprivation-type curiosity, and student engagement in science classes between male and female students. Additionally, correlation analysis was conducted to determine the correlation between variables. Lastly, we studied the extent to which interest and curiosity in science contribute to students' engagement in science classes. The results were as follow. First, the averages of individual interest toward science, interest-type curiosity, and deprivation-type curiosity were statistically significantly higher for male students than for female students. However, there was no difference between male and female students in students' engagement in science classes. Second, the correlation between individual interest toward science, interest-type curiosity, lack-type curiosity, and the subdimensions of students' engagement in science classes was above medium, except for social engagement, which showed a low correlation. Third, students' engagement and behavioral engagement in science class, individual interest, interest-type curiosity, and deprivation-type curiosity, in the affective engagement, individual interest and interest-type curiosity, in cognitive participation, individual interest and deprivation-type curiosity, and in social participation, interest-type curiosity were appeared to have an effect, respectively. Based on this study, some suggestions are as follows. First, there is a need to consider female student-friendly teaching methods that can increase female students' individual interest, interest-type curiosity, and deprivation-type curiosity in science classes. Second, considering that while learning is a personal activity, class is a social activity, research is required into what factors affect social engagement in science class. Third, considering that interest, curiosity, and student engagement are closely related to learning motivation, it is thought more research is needed on how they influence each other